An in vitro scanning electron microscopic study comparing the efficacy of passive ultrasonic and syringe irrigation methods using sodium hypochlorite in removal of debris from the root canal system.

OBJECTIVE To evaluate and compare the cleaning ability of the more biocompatible 1% sodium hypochlorite (NaOCl) with passive ultrasonic irrigation (PUI) to that of 2.5% NaOCl with syringe method irrigation. MATERIAL AND METHODOLOGY Thirty-six extracted permanent single-rooted mandibular premolar teeth were decoronated at the cemento-enamel junction and divided randomly into four groups (nine in each group) after biomechanical preparation. Group 1: Control group - normal saline was used as an irrigant solution. Group 2: PUI with 1% NaOCl. Group 3: syringe irrigation with 1% NaOCl. Group 4: syringe irrigation with 2.5% NaOCl. Roots were split and canal walls were examined at the apical third at 1,000X magnification in a scanning electron microscope (SEM). Debris scores were recorded using a scoring scale. Means were tested for significance using nonparametric Mann-Whitney U and chi-square tests. RESULTS Group 2 showed the lowest mean score of 0.33 compared to the other groups and Group 1 had the highest mean score. Significant difference was found when PUI with 1% NaOCl (Group 2) was done compared to syringe irrigation with 1% NaOCl (Group 3, p=0.001), and syringe irrigation with 2.5% NaOCl (Group 4, p=0.002). CONCLUSION PUI with 1% NaOCl is more effective in removal of debris from the root canal system than syringe irrigation with a higher concentration of 2.5% NaOCl.